Definition of fast-dye:
(adj) :
(dated) Firmly or securely fixed in place; stable.
(adj) :
Firm against attack; fortified by nature or art; impregnable; strong.
(adj) :
(of people) Steadfast, with unwavering feeling. (Now mostly in set phrases like fast friend(s).)
(adj) :
Moving with great speed, or capable of doing so; swift, rapid; light.
(adj) :
(nuclear physics, of a neutron) Having a kinetic energy between 1 million and 20 million electron volts; often used to describe the energy state of free neutrons at the moment of their release by a nuclear fission or nuclear fusion reaction (i.e., before the neutrons have been slowed down by anything).
(adj) :
Of a place, characterised by business, hustle and bustle, etc.